We have a few holding companies a few levels above the operating company. The only integration that is done is to create a company in the general ledger for predominately tax purposes. Our tax department seems to be the only department that has a use for it in the system. Some stock entries might be done to have some record of that.
The Finance staff finds it to be additional work to enter journal entries and there are more reconciliations that have to be maintained. However, it makes the tax department happy, so that is a strenth. Seriously, though, it is a strenth to have some processes in place with regard to holding companies.